fix :langchain for text classification task

[Prikshit7766]

Description

For text classification task and hub - huggingface , we have don't need to install langchain. This bug is due to the import statement in In the transformers_modelhandler.py

• fix: Bug: langchain for text classification task #741

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I've added Google style docstrings to my code.
• I've used pydantic for typing when/where necessary.
• I have linted my code
• I have added tests to cover my changes.

Usage

from langtest import Harness
harness = Harness(
            task = "text-classification",
            model={"model":'lvwerra/distilbert-imdb', "hub":"huggingface"},

        )

Screenshots (if appropriate):